For the crumbles, melt 100 g of fat and let it cool down. Mix 200 g flour, 100 g sugar and 1 teaspoon baking powder. Add egg yolk, lime zest and melted fat to the flour mixture. First work into crumbles with the dough hooks, then with your hands, set aside.
Cream 250 g fat, salt, 225 g sugar and vanillin sugar. Stir in the eggs one after the other. Mix 450 g flour and 1 packet of baking powder, sieve on top. Stir in together with the cream. Grease the fat pan of the oven (32 x 39 cm) and dust with flour.
Add the dough and smooth it down. Drain mandarin oranges on a sieve and spread them on the dough, sprinkle with crumbles. Bake in the preheated oven (electric cooker: 175 °C/ convection oven: 150 °C/ gas: level 2) for about 40 minutes.
Let it cool down on a cake rack.